Synthesis And Characterization Of (Ni,Sb)-co-doped Rutile Ceramic Pigment

Yellow ceramic pigment is one of the important colorants in ceramic industry.In general,conventional yellow pigments like lead chromate?PbCrO₄?,antimony yellow?Pb₃?SbO₄?₂?and cadmium yellow?CdS?are used.However,the application of these yellow pigments is restricted because of their toxicity of chemical elements like Cr,Cd,Sb and Pb,which are harmful to humanbeing and environment.Also,praseodymium-doped zirconium silicate?Pr-ZrSiO₄?as a yellow ceramic pigment is popular,which needs to be fabricated with costly rare-earth element?i.e.,Pr?.It is thus important for ceramic industry to develop environmental-friendly and high cost-effective yellow ceramic pigments.?Ni,Sb?-co-doped rutile pigment is environment-friendly,high cost-effective,and has great chemical and thermal durabilities since Ni²⁺and Sb⁵⁺ions are absolutely doped into rutile phase.The existing?Ni,Sb?-co-doped rutile pigment has some deficiencies,such as a low yellow hue,a high green hue and insufficient brightness.Therefore,it is necessary to adopt effective and low cost methods to improve the color performance of?Ni,Sb?-co-doped rutile pigment and obtain a yellow ceramic pigment with a bright yellow hue.In this dissertation,?Ni,Sb?-co-doped rutile pigment was prepared by a solid-state reaction method,the effects of parameters?i.e.,Sb/Ni ratio,Ni content,dispersant,dispersant dosage,soaking time and sintering temperature?on the reaction process of the prepared pigments were investigated.The results show that the material mixtures ground with 1.0 wt.%AD-8030 have a narrower particle size distribution and a smaller median particle size?i.e.,0.64?m?.The more Ni²⁺ions are doped into rutile phase,which can result in a higher b^*value?yellow value?of pigment when Sb/Ni ratio,Ni content,soaking time and sintering temperature increase.In addition,?Ni,Sb?-co-doped rutile pigment presents a good color performance?i.e.,L^*=87.10?a^*=-4.26?b^*=60.05?with a bright yellow hue when Sb/Ni ratio is 2:1,Ni content is 3 wt.%,soaking time is 60 min and sintering temperature is 1100?.?Ni,Sb?-co-doped rutile yellow ceramic pigment was synthesized via mechanical activation in different liquid media?i.e.,water or alcohol?and subsequnet solid-state reaction.The effects of mechanical activation,grinding way of materials,liquid medium and sintering temperature of precursors on the synthesis process of?Ni,Sb?-co-doped rutile pigment were investigated.The results show that anatase gradually transforms into rutile,the b*value?yellow value?and a*value?red value?of pigment increase while the L^*value?bright value?decreases when sintering temperature increases.Mechanical activation is effective to decrease the particle size and the crystallinity,destroy the crystal structure,enhance the reactivity of the precursor,favor the doping of Ni²⁺and Sb⁵⁺ions into TiO₂,thus lowering the formation temperature of rutile and enhancing the color performance of pigment.Compared to the materials ground firstly and then mixed,the materials mixed before grinding is more effective to accelerate the doping of Ni²⁺and Sb⁵⁺ions into TiO₂ and lower the formation temperature of rutile.The mechanical activation in alcohol is more effective to decrease the particle size of precursor,while the mechanical activation in water is more effective to accelerate the doping of Ni and Sb ions into TiO₂,favor the formation of new phases?brookite and rutile?,decrease the agglomeration of pigment and lower the formation temperature of rutile.The color parameters of Ti_0.91Ni_0.03Sb_0.06O₂ pigment from raw material mixture ground in water for 2.0 h and sintered at 1100?is L*/a*/b*=85.85/-2.54/62.83,for Ti_0.85Ni_0.05Sb_0.10O₂ pigments from the mixture ground in alcohol for 3.0 h and sintered at 1100?is L*/a*/b*=81.47/0.98/65.82.In addition,a small color difference(?E*_ab)before and after thermal/chemical resistance tests of?Ni,Sb?-co-doped rutile pigment synthesized via mechanical activation-assisted solid-state reaction indicates that the pigment possesses great thermal and chemical durabilities.?Ni,Sb?-co-doped rutile yellow ceramic pigment was synthesized via a sol-gel method,the effects of parameters?i.e.,molar ratio of HAc?acetic acid?/TBB?butyl titanate?,H₂O/TBB and CH₃H₂OH/TBB,pH value of solution,hydrolysis temperature and sintering temperature?on the synthesis process of?Ni,Sb?-co-doped rutile pigment were investigated.The results show that the geling time of precursor decreases,the particle size of precursor first decreases and then increases,and the b*value?yellow value?of pigment increases with the decrease of HAc/CH₃H₂OH and the increase of H₂O,pH value of solution and hydrolysis temperature.However,Ti?NO₃?phase appears in the pigments at short geling time of precursor.Anatase gradually transforms into rutile,and Ni²⁺and Sb⁵⁺ions dope into TiO₂ continually when the sintering temperature increases,resulting in the increase of the b*value?yellow value?and a*value?red value?of pigment and the decrease of the L^*value?bright value?.In addition,the superior color performance?i.e.,L^*=82.87?a^*=-1.08?b^*=60.43?of?Ni,Sb?-co-doped rutile yellow ceramic pigment is achieved under the optimum conditions?i.e.,molar ratio of HAc/TBB of 1:1,molar ratio of H₂O/TBB of 4:1,molar ratio of CH₃H₂OH/TBB of 15:1,pH value of solution of 1.5,hydrolysis temperature of 60?and sintering temperature of 1000??.Finally,this dissertation gives the conclusions obtained through experiments and analysis and some prospects for the future work.